For example, JP-A-2005-205943 discloses an action estimating apparatus mounted in a vehicle for estimating an action performed by an occupant of the vehicle. The action estimating apparatus of JP-A-2005-205943 includes an image device and an image processing device. The image device obtains a photograph including a driver. The image processing device determines existence of a dangerous action based on the photograph obtained by the image device. The dangerous action is, for example, an action (telephone use action) for using a cellular phone when a driver is driving the vehicle. In the image processing device, a predetermined region, in which a hand of a driver is located at a high possibility in the telephone use action, is beforehand set around the face of the driver in a photographic image. When the hand is continually located in the predetermined region of the photographic image for a predetermined time period or more, it is determined that the driver is performing the telephone use action. In addition to the telephone use action, the dangerous action may further include lifting of a hand from a steering wheel to manipulate an air-conditioner or a navigation device and lifting of a hand from a steering wheel to swing a shoulder and an arm. However, the action estimating apparatus of JP-A-2005-205943 only determines whether the telephone use action is performed according to a position of a hand in a photographic image. Thus, even when a driver performs a dangerous action other than the telephone use action, the action estimating apparatus cannot detect the dangerous action.